1. Field of the Invention
This invention relates to glazing systems for building walls, particularly of the curtain wall type.
2. Description of the Prior Art
In recent years an increasing number of buildings have been constructed with windows and other wall panels supported in elastomeric gasket strips which sealingly retain and cushion the wall panels. Such gasket strips generally comprise an elongated elastomeric body having grooves therein for receiving the edges of glass or other rigid sheets to be joined. The usual gasket strip also includes a wedge-shaped member insertable in a wedge receiving recess in the body of the strip. In such strips a portion of the gasket is bent back to allow the edge of the glass to be inserted into the groove, and then the wedge-shaped member is installed, whereby the elastomeric material is crowded to cause the groove to engage the glass or other rigid sheet more tightly. Such known gasket strips provide a resilient weather seal around the periphery of the panel. Such a gasket strip is disclosed, for example, in U.S. Pat. No. 3,068,617 to Borski. Such gaskets have been highly successful, but present difficulties in opening the groove to insert the glass, and in proper installation of the wedges, special tools usually being required.
In some installations conventional masonry and like building walls are replaced by a form of curtain wall construction consisting of an open structural frame work that either supports a panel within the open space defined by the structural frame work or has separate panel framing elements attached to one face of the structural frame work. The structural frame work and panel framing elements are generally composed of a number of extruded metal members that may be joined to form a single module, but are more frequently joined into a multiple module grid structure. A problem which has arisen in such installations involves the provision of a thermal barrier between the panel members and the grid members to prevent heat transfer from one member to thhe other, while providing a curtain wall system that is capable of fully meeting design specifications, both with respect to esthetics and performance. At the same time it is desirable to provide a sound barrier to decrease sound transmission between the exterior and interior of the building.
Systems attempting to solve these problems have heretofore been designed, as shown, for example, in U.S. Pat. Nos. 3,336,707 to Horgan, Jr., 3,488,906 to Brooks, and 3,699,735 to Smith.
Although the glazing systems disclosed in these patents have been found acceptable in many installations, problems of esthetics and difficulty of assembly have occurred in many cases. For example, the structure disclosed by Horgan, Jr. must be assembled from scaffolds on the outside of the building unless the building owner is willing to have the glazing gaskets with the wedges on the inside of the building. This is due to the fact that it is necessary to insert the wedges to clamp the panels after the panels are in place. Thus if, as is usually the case, the building owner prefers to have the smooth metal extrusions on the inside, scaffolding must be erected for construction of the curtain wall from the outside.
Brooks avoids this problem, but only by use of a large number of complex pieces in his assembly, so that construction is made more difficult and time consuming.
Smith's design can also be constructed from the interior of the building with the gasket on the outside but in this design difficulty is encountered in opening the grooves of the gasket to insert the panels, and then holding the gasket and panels in place while inserting the wedge to clamp the panels, followed by attaching this assembly to the metallic structure.
Such glazing systems as these utilize the gasket as a structural member; i.e., in addition to having the gasket function of sealing, the gasket has a structural support function of providing support for the wall panel members, such as glass. Thus such gaskets differ considerably from ordinary gaskets which provide only a sealing function, such as around refrigerator doors and the like.